Describe what should be investigated or refactored

!2170 migrated many packager receivers dealing w/ create operations from src/pkg/packager/create.go to src/pkg/packager/create_stages.go as well as cleaned up their naming and more properly grouped certain logic (like differential).

However, this resulting file is too large and cumbersome, as well the create process overall could use some library TLC.

Links to any relevant code

src/pkg/packager/create_stages.go

#2170 (comment)